In recent years, an erasing apparatus which sequentially takes in a sheet on which an image is formed using decolorable coloring material, and heats the sheet while pressurizing the sheet, to perform erasing processing of the image is known. The decolorable coloring material is coloring material which is decolored by being heated at a prescribed temperature. The image which has been subjected to the erasing processing is decolored, to be erased visually. This erasing apparatus is used for the purpose of promoting reuse of a sheet. The erasing apparatus detects presence/absence of a mark indicating the limitation of number of uses of a sheet and the degree of deterioration of a sheet from the sheet, and judges whether or not the sheet is reusable based on this detection result.
However, the above-described conventional erasing apparatus executes erasing processing to a sheet of a processing object in the same manner, upon accepting an erasing request by a user, even when a sheet on which an image including an important image or a confidential image is formed is mixed in sheets of processing objects. Further, the conventional erasing apparatus does not perform processing to the sheet after the erasing processing for sorting a sheet on which an image including an important image or a confidential image has been formed and an otherwise sheet. Accordingly, the conventional erasing apparatus has a problem of security management, in a point of safe discharge of a sheet on which an image including an important image or a confidential image has been formed.